1. Field of the Invention
This invention relates to reciprocating tools, and in particular to a hydraulic impact tool.
2. Description of the Prior Art
Soil tampers and compactors are utilized for compacting dirt and the like in fills such as around newly installed posts and poles. Such soil tampers utilize tamping elements which are reciprocated at relatively high frequency, such as over 1000 strokes a minute, while delivering a substantial force. Conventionally, such soil tampers have been pneumatically operated as illustrated in U.S. Pat. No. 2,748,750 of S. Altschuler, disclosing a Vibrationless Pneumatic Impact Tool. Such pneumatic tampers have a serious disadvantage of being relatively noisy and dirty in the sense that a substantial amount of dust is raised in the normal use thereof.
More recently, hydraulic soil tampers have been developed which are substantially quieter and which raise substantially less dust in the operation thereof. A problem, however, arises in connection with the use of such hydraulic impact tools in that the conventional hydraulic impact tools are relatively difficult to handle because of substantial uncontrolled bounce. Such bounce is aggravated where the material being compacted is relatively rigid and the use of such conventional tools requires substantial effort on the part of the operator to maintain the tool in the tamping disposition.
Illustrative of such tools are those disclosed in U.S. Pat. Nos. 2,470,087 (Adams); 3,314,488 (ChesterBrowne et al.); 3,468,222 (Cordes et al.); 3,522,269 (Arndt); and 3,554,085 (Butterworth).